Ignition system for an internal combustion engine

ABSTRACT

An ignition system has a switching transistor having an emittercollector path connected in series with the primary winding of an ignition coil. The latter series combination is connected between voltage supply leads. A driver circuit has a control electrode and controls the conductive state of the switching transistor. An ignition breaker switch has alternating open and closed intervals in response to rotation of the engine. The breaker switch may have the undesirable property that it closes mometarily during the open interval shortly after opening of the breaker switch. A signal control circuit is connected to the ignition breaker switch and to the control electrode to make the emitter-collector path of the switching transistor conductive when the breaker switch is closed and to make it nonconductive when the breaker switch is open. An energy storage element, either the primary winding itself or a capacitor, stores energy prior to the closing of the breaker switch during an open interval of said switch, and the stored energy is used to maintain the control electrode at a potential to maintain the transistor path open irrespective of the closing of the breaker switch during an open interval of the same.

United States Patent [191 Steinberg etal.

[ Dec. 17, 1974 1 IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE 73Assignee: Robert Bosch GmbH,Stuttgart,

Germany [22] Filed: July 19, 1972 [21] Appl. No.: 273,185

[30] Foreign Application Priority Data July 24, 1971 Germany 2137204[52] U.S. Cl......' 123/148 E, 123/148 S [51] Int. Cl. F02p l/00 [58]Field of Search 123/148 E [56] References Cited UNITED STATES PATENTS3,144,012 8/1964 Tarter 123/148 E 3,260,251 7/1966 Lange 123/148 E3,291,110 12/1966 Peters 123/148 E 3,564,581 2/1971 Winterburn 123/148 E3.581.726 6/1971 Plume 123/148 E 3.651.793 3/1972 Roth l 123/148 E3.658.044 4/1972 Safstrom 123/148 E 3,666,989 5/1972 Boyer 123/148 E3.716.037 2/1973 Jacobs 123/148 E Moran 123/148 E Hohne 123/148 EPrimary ExaminerCharles J. Myhre Assistant Examiner-Ronald B. CoxAttorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT An ignitionsystem has a switching transistor having an emitter-collector pathconnected in series with the primary winding of an ignition coil. Thelatter series combination ,is connected between voltage supply leads. Adriver circuit has a control electrode and controls the conductive stateof the switching transistor. An ignition breaker switch has alternatingopen and closed intervals in response to rotation of the engine. Thebreaker switch may have the undesirable property that it closesmometarily during the open interval shortly after opening of the breakerswitch. A signal control circuit is connected to the ignition breakerswitch and to the control electrode to make the emitter-collector pathof the switching transistor conductive when the breaker switch is closedand -to make it nonconductive when the breaker switch is open. An energystorage element, either the primary winding it self or a capacitor,stores energy prior to the closing of the breaker switch during an openinterval of said switch, and the stored energy is used to maintain thecontrol electrode at a potential to maintain the transistor path openirrespective of the closing of the breaker switch during an openinterval of the same.

41 Claims, 5 Drawing Figures IGNITION SYSTEM FOR AN INTERNAL COMBUSTIONENGINE BACKGROUND OF THE INVENTION The present invention relates toignition systems, and particularly to an ignition system for an internalcombustion engine which generates sparks in response to opening andclosing of the ignition breaker switch whose quality is not deterioratedby the momentary closing of the breaker switch during an open intervalthereof.

Ignition systems already known which have an ignition coil having aprimary and a secondary winding. In such systems, the secondary windingis typically con nected to at least one spark plug whereas the primarywinding is connected in series with a switching element. The switchingelement may consist of a switching transistor whose emitter-collector isconnected in series with the primary winding. A control circuit isprovided with such ignition systems which is connected to the base ofthe switching transistor and which causes the transistor to becomeconductive when the ignition breaker switch is closed and is caused tobecome nonconductive when the breaker switch is open. In this manner,whenever, the breaker switch is closed, current is permitted to flowthrough the primary winding whereas whenever the breaker switch is open,such current flow is inhibited.

In ignition systems of the above type; the current passing through theignition breaker switch is relatively small so as not to have an adverseeffect on the operation of the'engine due to the burning out of theswitch contacts. The utilization of small currents in the braker switchlargely removes this danger.

However, the systems of the type described above have disadvantages.Thus, although the breaker switch is designed to open and close inresponse to rotation of a rotary element of the internal combustionengine, the switch does not always properly open. Thus, due to almostunavoidable clearances and the manufacturing tolerances in suchswitches, the resulting play often causes the switch to closemomentarily for a short period of time subsequent to opening in the openinterval, after which the switch reopens and stays open for theremainder of the open interval. Such action of the switch not onlycauses heavy loading of the switching transistor, but also has anadverse effect on the quality of the spark produced in the secondarywinding and may result in missing of ignitions in some of the cylindersto thereby result in inefficient and rough operation of the engine.

SUMMARY OF THE INVENTION:

Accordingly, it is an object of the present invention to provide anignition system for an internal combustion engine which does not havethe disadvantages of the systems known in the prior art.

It is another object of the present invention to provide an ignitionsystem which is simple in construction and economical to manufacture.

It is still another object of the present invention to provide anignition system of the type under discussion wherein the sparksgenerated are not deteriorated by the closing action of the breakerswitch during an open interval thereof.

It is a further object of the present invention to provide an ignitionsystem which does not produce loading in the transistor connected inseries with the primary winding due to momentary closings of the breakerswitch during an open interval thereof.

With the above objects in view, the present invention is for an ignitionsystem for an internal combustion engine having a rotary element. Thecombination comprises an ignition coil with primary and secondarywindings. An ignition breaker switch is provided which respectivelyopens and closes for alternating first and second intervals determinedby said rotary element of the engine and which may exhibit a tendency toclose during said first intervals. Switching means are provided whichare connected in series with the primary windings, said switching meansbeing arranged to open to thereby block current flow in the primarywinding and to close to thereby permit current to flow through theprimary winding. First circuit means are provided which are connectedbetween the ignition breaker switch and said switchingmeans to open the"latter when the ignition breaker switch opens and to close saidswitching means when the ignition breaker switch closes. Second circuitmeans are provided which are connected to said first circuit means formaintaining said switching means open irrespective of closing of saidignition breaker switch during at least portions of said firstintervals. I l

According to one embodiment of the present invention, said secondcircuit means cooperates with the primary winding, the latter acting asan energy storing element. In this case, the primary winding storesenergy prior to a closingof the breaker switch duringsaid portions ofsaid first intervals.'Part of the stored energy cooperates with saidsecond circuit means to maintain said switching means open irrespectiveof closing of said ignition breaker switch during said portion of saidfirst intervals. In accordance with another embodiment, said secondcircuit means includes capacitor means which store energy prior toclosing of said ignition breaker switch during said portions of saidfirst intervals to maintain said switching means open during saidportions of said first intervals.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing. I

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic of an ignitionsystem in accordance with the present invention, wherein the primarywinding of the ignition coil is used as an energy storing element;

FIG. 2 is a schematic of a secondembodiment of the invention as shown inFIG. 1',

FIG. 3 is a schematic of a third embodiment of the invention as shown inFIG. 1, wherein a storage capacitor is added to cooperate with theprimary winding;

FIG. 4 is a schematic of an ignition system in accordance with thepresent invention, wherein a capacitor is utilized to store energy;energy; and i FIG. 5 is a schematic of another embodiment of theinventionas shown in FIG. 4. v

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the Figures,wherein similar reference numerals have been utilized for the same partsthroughout, and first referring to FIG. 1, an ignition system inaccordance with the present invention is shown to have an ignition coil11 which has a secondary coil 12. The secondary coil 12 is connected atone of its terminals to one of its terminals to one of the terminals ofaspark plug 13. Ignition coil 11 also has a primary winding 14 which isconnected to an npnswitching transistor 15. The specific construction ofthe ignition coil 11 is well known and does not form part of the presentinvention. Although the secondary winding 12 has been shown to beconnected to only one spark plug 13, it is understood that, if aninternal combustion engine has more than one cylinder, the secondarywinding 12 may be connected to all the spark plugs by means of aconventional distributor (not shown). With such a distributorarrangement, successive voltages induced in the secondary winding 12 canbe sequentially applied to the spark plugs in a predetermined order.

The transistor 15 has an emitter 16 and a collector 17 which forms anemitter-collector path which is connected in series with primary winding14.

Continuing to first describe the conventional details of the ignitionsystem, an ignition breaker switch is indicated by the reference numeral18. The breaker switch cooperates with a rotary element (not shown) inthe combustion engine in a well-known manner so as to open and closesaid switch in dependence on the position of the rotary element.Particularly, the breaker switch 18 opens and closes alternatingly. Thetimes when the breaker switch 18 is open will be referred to asthe openinterval and when the breaker switch 18 is closed will be referred to asthe closed interval. Ideally, the open and closed intervals are sharplydefined so that the state of the breaker switch 18 is solely defined bythe position of the rotary element. Thus, for continuous rotation of therotary element in one direction, the breaker switch opens at apredetermined position of the rotary element and remains opened untilthe rotary element has reached a second position. At such time, thebreaker switch 13 closes and remains closed until a third position ofthe rotary element has been reached. Upon reaching the fourthpredetermined position, the breaker switch 18 opens once again. However,as described above in connection with the background of the invention,these breaker switches do not always operate in such an ideal fashion.The imperfect action is partly attributable to the play in said switchescaused by clearances and manufacturing tolerances. For this reason, suchswitches often have a tendency to open improperly. Thus, once thebreaker switch 18 opens, it will often close again at least momentarilyduring said first intervals. More commonly, such breaker switches closeshortly after initial opening, after which the switch opens once againand remains open for the remainder of the open interval.

The ignition system 10 is connectable to a battery 19 whose negativeterminal, in the embodiments to be described is connected to the circuitground 20. A voltage supply lead 21 is connected to the ground 20 andprovides said potential to the ignition system 10. A single pole, singlethrow switch 22 is connected between the positive pole of the battery 19and a positive voltage supply lead 23.

The ignition circuit is controlled by the breaker switch 18 electrode 24whose potential is controlled by the breaker switch 18 as will presentlybe described. Each of the embodiments to be described has an electrode24, the potential thereon being effective for actuating a switchingtransistor in series with primary winding. As will be presentlydescribed, each of the embodiments can be functionally broken down intotwo cir cuits. The first circuit is generally connected between theignition breaker switch 18 and the switching transistor 15 (or 68 inFIGS. 4 and 5) to open the latter when the ignition breaker switch opensand to close the switching transistor 15 when the ignition breakerswitch closes. Thus, the first circuit serves the function of openingand closing the switching transistor 15 under ideal operating conditionsof the breaker switch.

The second circuit, which will be identified for each of the embodimentsthat follow, is connected to the first circuit and is so arranged thatit maintains the switching transistor 15 open irrespective of closing ofthe ignition breaker switch 18 during at least portions of the ideallyopen intervals. The first circuit can be further broken down into twosub-circuits which are readily identifiable in all of the embodiments.Thus, the first circuit includes a driving circuit which is connected tothe switching transistor 15 and is connected to the control electrode24. The potential applied to the control electrode 24 determines whetherthe driving circuit opens or closes the switching transistor 15.Secondly, the first circuit includes a control circuit which isconnected to the breaker switch 18 and to the control electrode 24 forgenerating signals during the open and closed intervals of the breakerswitch. Thus, it is seen that the control electrode 24 fuctionallydivides the first circuit into the two latter sub-circuits justdescribed, the control circuit controlling the potential of the controlelectrode 24 as a function of the condition of the breaker switch 18,while the driving circuit responding to the potential at the electrode24 to thereby control the operation of the switching transistor 15.

The switching transistor 15 has a base 25 which is connected to thedriving circuit described above, and presently to be defined. Byapplying suitable voltages to the base 25 in relation to the emitter 16,the switching transistor 15 can be open or closed to thereby make theemitter-collector path 16-17 conductive or nonconductive. Since theswitching transistor 15 is connected in series with the primary winding14, the current flow to the latter is dependent on the conductive stateof the switching transistor 15. Thus, when the switching transistor 15is conductive, current can flow from the positive lead 23 to the primarywinding 14, to the emitter-collector path l6, l7, and to the ground lead21. However, when the switching transistor is nonconductive, currentthrough the primary winding 14 is inhibited, except as will presently bedescribed.

Referring to FIG. 1, the control circuit, referred to above, forregulating the voltage at the control electrode 24 as a function of theopen-closed conditions of the breaker switch 18, consists of a controlresistor 26 connected between the positive lead 23 and the controlelectrode 24 and a resistor 27 connected between the control electrode24 and one terminal of the breaker switch 18, the other terminal of thelatter being connected to the ground lead 21. The resistances 26 and 27comprise a voltage divider whose tap point is connected to the controlelectrode 24. While the voltage divider is always connected to thepositive lead 23 through the control resistor 26, it is connectable tothe ground leaf 21 only through closing of the breaker switch 18. Thecontrol resistor 26 serves as a voltage dropping element to therebyapply a potential difference between the positive lead 23 and thecontrol electrode 24 when current flows through the control resistance26 as will presently be described. It is not essential that the controlelement 26 be a resistor as shown but can be any element which exhibitsa voltage drop upon the passage of current therethrough, e.g., a diode(not shown) having its cathode connected to the positive voltage lead 23and its anode connected to the control electrode 24 to thereby conductcurrent from the latter to the former. In the event, if a diode is used,it may be desirable to connect a shunt capacitance thereacross (notshown).

The values of the resistors 26 and 27 are so selected that a relativelysmall voltage is developed across the resistor 26 when the breakerswitch 18 is closed. Since the voltage developed across the resistor 26is applied across an emitter-base of a transistor, to be described, forthe purpose of forward biasing or cutting off the same, the voltage tobe developed across the resistor 26 will typically be approximately 0.7to 1 volts. With a battery voltage of 12 volts, for example, the ratioof the resistances of the resistor 27 to the resistor 26 is greaterthan 1. Thus, with this arrangement of the control circuit, theresistance of resistor 26 is much smaller than the resistance ofresistor 27.

The primary winding 14 is connected in series with the emitter-collectorpath l6, 17 of the switching transistor to form a tap point 28. Asdescribed above, when the switching transistor 15 is conductive, currentflows through the primary winding 14. In the embodiment underdiscussion, the primary winding 14 is utilized as an energy storageelement which cooperates with the second circuit described above tomaintain the switching transistor 15 open or non-conductive during theopen intervals of the breaker switch 18 irrespective of closing of thebreaker switch 18 during said open intervals. To achieve these desiredresults, the second circuit comprises a discharge conductor path 28aconnected to the tap 28. The discharge conductor 28a is connected to aresistor 29 which serves to limit the current flowing through thefollowing series connected diode 30, the latter being connected to thecontrol electrode 24 and to the tap points formed-by the resistors 26and 27. Thus, the second circuit in this instance comprises thedischarge conductor 28a, the limiting resistor 29 and the diode 30. Thissecond circuit is connected to the tap point 28 and permits current flowfrom the primary winding 14 when the switching transistor 15 is placedin its non-conductive state. The diode 30 is arranged with its cathodeconnected to the control electrode 24 and its anode connected to thelimitingresistance 29 as shown to thereby permit current flow from thetap point 28 towards the control electrode 24. Such current flow.presently to be more fully described, is generated by the stored energyin the primary winding 14.

The control electrode 24' is connected to the base 31 of a pnp couplingtransistor 32 which forms a part of the driving circuit mentioned above.The coupling transistor 32 has its emitter 33 connected to the positivelead 23 and its collector 34 connected to a voltage divider whichcomprises series connected resistors 35 and 36. The voltage divider hasa tap point 37 which is connected to the base 25 of the switchingtransistor 15. Thus, the driving circuit in this instance comprises thecoupling transistor 32 and the resistors 35 and 36. The resistor 36 isalso connected to the ground lead 21 so that the voltage divider 35, 36as well as the series connected emitter-collector path 33, 34 areconnected between the positive lead 23 and the negative lead 21.

The operation of the embodiment illustrated in FIG. 1 will now bedescribed. Examining first the closed intervals of the breaker switch18, the closing of the switch 18 places the terminal of the resistor 27connected thereto at the ground potential. This places the voltagedivider 26, 27 across the battery 19 to thereby apply a preselectedvoltage to the control electrode 24, as described above. Thus, the base31 of the coupling transistor 32 is made more negative than the emitterof said transistor to thereby cause the latter to become conductive.Emitter-base current flows through the control electrode 24, theresistor 27 and. theclosed breaker switch 18 to the ground lead 21. Itshould be noted in this connection, that if a diode were to beutilized-in place of the resistor 26, as suggested above, the sameemitter-base current would flow to permit the coupling transistor 32 tobecome conductive in the same manner. When the emitter-collector path33, 34 becomes conductive, a current flows throughthe resistors 35 and36 forming the voltage divider, and a positive potential with respect tothe ground is applied to the base 25 by virtue of this connection" withthe. tap point37. The resistors 35 and 36 are so'selected that asufficiently positive'voltage is applied to the base 25 with respect tothe ground potential which exist at the emitter 16 to causetheemitter-collector path 16, 17 of the switching transistor 15 tobecome conductive. In the embodiment under discussion, the currentflowing through the primary winding 14 at said'times, namely during theclosed intervals of the breaker switch 18, ceases magnetic energy to bestored in the primary winding l4.'ln the driving circuit the couplingtransistor 32 and the voltage divider, comprising the resistances 35 and36, are so arranged and the values of the latter are so selected so thatthe switching transistor 15 becomes highly conductive to present avirtual short circuit between the tap 28 and the ground lead 21. Thus,during the times when the switching transistor 15 is so heavilyconducting, hardly any current is diverted into the discharge conductorpath 28a.

First assuming ideal operation of the breaker switch 18, it cantherefore be assumed that the second circuit comprising of the dischargeconductor 28a, the limiting resistor 29 and the diode 30 are notconnected in the circuit. Now, when the breaker switch 18 opens,emitter-base current flowing through the emitter-base path 33, 31 isprevented and the coupling transistor 32. becomes non-conductive. Withno current flowing through the emitter-collector path 33, 34, thevoltage at the tap 37 of the voltage divider 35, 36 is' the same as theground potential and the base of switching transistor 15 is therebyplaced at the same potential as the emitter 16. By thus removing thepositive biasing voltage from the base 25, the switching transistorbecomes non-conductive and the field which has been built up around theprimary winding 14 begins to collapse to the drop in current in thelatter. An' induced voltage inv the secondary winding 12 .is therebygenerated in accordance with well-known principles, the turn ratiobetween the primary and secondary windings being so selected that asufficiently high voltage is attained which will be effective to producea spark across the spark plug 13.

The effect of a non-ideal breaker switch 18 will now be considered. Asdescribed above, such a switch will not open exactly during the ignitiontime but will momentarily close thereafter and thereafter open again andremain open for the balance of the open interval. As described above,when no precautions are taken to compensate for such disturbances, thereis a strong loading of the switching transistor 15 and may result'inignition failure or missing. However, with the provision of the secondcircuit, namely the diode 30 and the limiting resistor 29, suchdisturbances are eliminated. In the closed period of the breaker switch18 the first circuit operates as described above. Now when the breakerswitch 18 opens for the first time after the closed interval, theemitter-collector path 1617 of the switching transistor 15 isinterrupted as is the current flowing through the primary winding 14.However, it is known that currents flowing in inductors resist abruptchanges and the current, due to the storage of the magnetic field aboutthe coil, tend to maintain the current flow. The current flowing in theprimary winding 14 initially flows from the positive supply lead 23through the primary winding 14 and through the emitter-collector path16-17. However, now that the emitter-collector 16-17 is closed, thecurrent is permitted to flow through the second circuit namely thedischarge conductor 280, the limiting resistor 29, the diode 30 and theresistor 26 and back to the primary winding 14 to thereby form a closedloop. As noted above, the resistor 26 is selected so that when thecurrent flowing in the latter loop flows therethrough, the voltagedeveloped across the resistor 26 is sufficient to maintain theemitter-base junction of the transistor 32 in the nonconductive state.Otherewise, the current through the loop is controlled by the value ofthe resistor 29. The

- resistor 29 is selected so that an appropriate cut-off voltage may bedeveloped across the transistor 32 emitter-base junction but to preventa substantial portion of the current originally flowing through theprimary winding 14 to be diverted into the second circuit. In thismanner, the change in current effected as a result of the turning off ofthe switching transistor 15 is still considerable and therefore asufficient voltage may be developed in the secondary winding 12 tocreate a spark across a spark plug 13. Now, when the breaker switchmomentarily closes after initial opening the base 31 of the transistor32 is made somewhat more negative by the voltage divider action of theresistors 26 and 27. However, the resistors 26 and 27 are so selected sothat, with the loop current above described, the voltage developedacross the resistor 26 is still sufficiently positive at the base 31 inrelation to the emitter 33 so that the transistor 32 remainsnon-conductive. Therefore even with a momentary closing of the breakerswitch 18, the coupling transistor 32 remains in its nonconductivecondition, just as though the breaker switch 18 had never closed. Thetime constant of the loop comprising the primary winding 14, thelimiting resistor 29, the diode 30, and the resistor 26 is so selectedthat the magnetic field discharges in the manner described for a longenough period after initial opening of the breaker switch 18 to includeall the anticipated times during the open interval during which thebreaker switch may momentarily closexln this manner, the momentaryclosings of the breaker switch 18 are masked out at the input to thedriving circuit so that insofar as the switching transistor 15 isconcerned it is only turned on and off as it would be by an idealbreaker switch 18. As soon as the stored energy has been anticipated,the current through the loop, and particularly the resistor 26 ceases toflow, and, by the time that the normal closing interval arrives, thecoupling transistor 32 is susceptible to be made conductive once againby the closing of the breaker switch 18 as described above. The closingof the breaker switch 18 will at this time again build up the magneticfield around the primary winding 14, which field will be utilized inconjunction with the second circuit to compensate for the imperfect,actual operation of the breaker switch.

The diode is provided in the loop so that during the conductive state ofthe emitter-collector path 16-17, no unnecessary current flows throughthe second circuit but all the current flowing into the collector 17 isprimary winding 14 current.

Four more embodiments of the present invention will now be described.Insofar'as similar elements used in FIG. 1 appear in the subsequentembodiment and serves similar functions, these will be designated by thesame reference numerals and will not be described in detail insofar astheir operation is concerned.

Referring to FIG. 2, the control circuit of the first circuit hassomewhat been modified, as to be described. The driving circuit of thefirst circuit, comprising the transistor 32 and the resistors 35 and 36,is identical with that in FIG. 1. However, the second circuit comprisingthe limiting resistor 29 and the diode 30 in FIG. 1 has been deleted anda new circuit has been substituted therefor. Now, the diode 48 isconnected between the two resistors 26 and 27 making up the voltagedivider of FIG. 1. Connected to the tap point 28 is a Zener diode 38connected in series with a limiting resistor 29, these series connectedelements being connected to the base 47 of a transistor 44. The emitter45 of this transistor is connected. to the negative supply lead 21 whilethe collector of the transistor 44 is connected to the base 42 of atransistor 39 through a resistor 43. The emitter 40 of the transistor 39is connected to the positive supply lead 23 while the collector of thistransistor is connected to a tap point formed by the connection betweenthe resistor 27 and the diode 48. The control electrode 24 of thedriving circuit is now connected between a tap point which is formed bythe connection of the resistor 26 with the anode of the diode 48. Thetransistor 39 is selected to be a pnp transistor while the transistor 44is an npn transistor.

The operation of the embodiment shown in FIG. 2 will now be described.The closing of the breaker switch l8at the beginning of a normal closedinterval causes the cathode of the diode 48 to be more negative than theanode thereof. Consequently, the diode 48 is made conductive and thecontrol electrode 24 is made more negative, as in the embodiment shownin FIG. 1. Consequently, the coupling transistor 32 as well as theswitching transistor 15 are made conductive, as already described. Whenthe switching transistor 15, however, is conductive, the tap point 28 isbrought to a potential very nearly that of the ground or the potentialat the negative supply lead 21. Whatever small positive potential existsat the collector 17, appears across the Zener diode 38 which is not,however, great enough to break down the latter. Consequently, thevoltage at the base 47 of the transistor 44 is substantially at theground potential and equal to the potential of the emitter 45. Thus, thetransistor 44 is in the non-conductive state and no current flows in thecollector 46 of transistor 44 or in the base 42 of the transistor 39.The emitter-collector path 40-41 of the transistor 39 is thusnon-conductive, and, for all practical purposes, the second circuit isnot present.

Now, when the breaker switch 18 is initially opened the switchingtransistor becomes non-conductive and the energy stored in the primarywinding 14 is diverted into the discharge conductor 28a. Theemittercollector path 16-17 no longer shorts the tap point 28 to thenegative lead 21, the voltage at the tap point 28 becoming sufficientlypositive so that the Zener diode 38 breaks down and maintains its Zenervoltage thereacross. The balance of the positive voltage at the tappoint 28 is applied to the base 47 of the transistor 44 which issufficiently positive with respect to the emitter 45 potential, that theemitter-collector path 45-46 of the transistor 44 becomes conductive.This causes a base current to flow in the base 42 of the transistor 39and the latter transistor similarly becomes conductive. The resistor 43is selected so that sufficient base current can flow in the base 42 inorder that the transistor 39 becomes highly conductive and creates asubstantial short circuit between the positive lead 23 and the cathodeof the diode 48. In fact, the cathode of the diode 48 is therebymaintained at a potential nearly equal to that of the positive supplyleads 23 and this is substantially independent of whether the breakerswitch 18 is opened or closed. Thus, the control electrode 24 ismaintained at its positive potential as long as energy from the primarywinding 14 maintains the transistors 44 and 39 in their conductivestates. During this time the control electrode 24 is maintained at asufficiently positive level so that the closing of the breaker switch 18momentarily after opening does not bring the control electrode 24 tosufficiently negative voltage which can cause the driving transistor 32to become conductive. The provision of the diode 48 between theelectrode 24 and the conducting collector 41 is to insure that thesomewhat more negative collector 41 relative to the lead 23 cannot makethe control electrode 24 sufficiently negative to make the transistor 32conductive. Thus, any difference in potential between the collector 41and the emitter 40 appears across the diode 48. In this manner, thevoltage of the control electrode 24 is almost identical with the voltageat the emitter 33. The resistor 43 serves tolimit the current flowing inthe emitter-base path 40-42 to thereby prevent the transistor 39 frombecoming damaged or destroyed. It should be noted, that except for theshort interval following initial opening of the breaker switch 18 whenthe stored energy in the primary winding 14 is being discharged, theembodiment shown in FIG. 2 operates similarly to the embodiment shown inFIG. 1 in respect to the normal opening and closing intervals.

As soon as the energy in the primary winding 14 has been dissipated, thevoltage across the Zener diode 38 falls below the Zener voltage orthreshold voltage thereof and insufficient base currents flow into thebase 47. Thus, the transistor 44 becomes non-conductive and base currentin base 42 ceases to flow to thereby make the transistor 39 similarlynon-conductive. The circuit is now in its initial condition describedabove and is ready for another closing of the breaker switch 18 tothereby reestablish a magnetic field about the primary winding 14.

The ignition circuit illustrated in FIG. 3 has been somewhat modified inthat the control circuit comprising the resistors 26 and 27 of FIGS. 1and 2 has been replaced by the resistor 26 which is now directlyconnected to the breaker switch 18. A diode 49 is connected to the tappoint formed by the connection of the two latter elements. The cathodeof thediode 49 is connected to a limiting resistor 57 which in turn isconnected to the control electrode 24. The driving circuit of the firstcircuit now merely consists of a driving transistor 52 whose collector55 is connected to the positive supply lead 23 through a collectorresistor 54. The base 56 forms the control electrode 24 and the emitter53 is connected to the negative supply lead 21'. The base 25 of theswitching transistor 15 is directly connected to the collector 55 of thedriving'transistor 52. The second circuit in the present embodimentcornprises a resistor 29 connected to the tap point 28 which isconnected in series with a resistor SO, the latter also being connectedto the negative supply lead 21. A storage capacitor 51 is connected inparallel with the resistor 50. The tap point formed by the connection.between the resistor 29 and is connected to the cathode of the diode 49.The diode 49 is arrangedso that its anode is connected tothebreakerswitch 18 and its cathode is connected to the junction betweenthe resistors 29 and 50 so that a current flow from the junction isblocked from flowing through the (110(1649 but instead must flow throughthe resistor 57. The driving. transistor 52 is an npn couplingtransistor.

Examining first the normally closed condition ofthe breaker switch 18,the anode of the diode 49 is placed at the potential of the negativesupply lead 21 and is thereby made non-conductive. Since the capacitor51 is originally discharged, the voltage applied between the cathode ofthe diode 49 and the resistor 57 is substantially equal to the groundpotential of the circuit, this voltage being applied to the base 56 orthe control electrode 24 to thereby maintain the emitter-collector path53-55 of the driving transitor 52 in the nonconductive state. With thetransistor 52 nonconductive, the collector 55 thereof is substantiallymore positive than the emitter 16 of the switching transistor 15, sothat the latter transistor becomes conductive by virtue of its base 25being connected to the collector 55. Consequently, the emitter-collectorpath 16-17 of the switching transistor 15 becomes highly conductive andbecomes saturated to thereby present an almost perfect short circuitbetween the tap point 28 and the negative supply lead 21. Under thiscondition, the voltage across the capacitor 51 cannot build to anysubstantial positive value so that the voltage transmitted to thecontrol electrode 24 remains to be sufficiently negative to therebymaintain the transistor 52 non-conductive.

However. as soon as the breaker switch 18 opens, the anode of the diode49 becomes positive with respect to its cathode by virtue of the formerbeing connected to the positive supply lead 23 through the resistor 26.Thus, a current flows from the positive supply lead 23. the resistor 26,the diode 49, the resistor 57, the control electrode 24 and the baseemitter path 56-53 of the transistor 52 to the negative supply lead 21.In this manner, the emitter-collector path 53-55 becomes conductive andthe base 25 of the transistor drops substantially in a negativedirection. This makes the emitter-collector path 16-17 non-conductiveand the current initially flowing in the primary winding 14 is at leastpartially diverted into the discharge conductor or branch-off lead 280.The discharge loop in the embodiment in FIG. 3 is as follows: Thebranch-off lead 28a, the resistor 29, the resistor 50, the battery 19,the switch 22 and the primary winding 14. Upon initial opening of theswitch 18, the discharge current begins to flow in the last-mentionedloop. The resistors 29 and 50 are so selected so that the dischargecurrent develops a sufficiently high positive voltage across theresistor 50 so that this voltage applied between the diode 49 and theresistor 57 will be of sufficiently high positive magnitude to maintainthe transistor 52 in its conducting state. Thus, should the breakerswitch 18 momentarily close, the transistor 52 will nevertheless remainconductive as long as the junction points between the resistors 29 and50 is ofa sufficiently high positive magnitude in respect to the emitter53 voltage. To somewhat prolong this effect, the capacitor 51 isconnected in parallel with resistor 50 so that some of the currentflowing through the resistor 29 is utilized to charge the capacitor 51to a positive level at its upper plate. Now, when the transistor 52 isin its conductive state, such conductive state is maintained by thedischarge of current from the capacitor 51 into the control electrode 24and the base emitter junction 56-53 of the transistor 52. Of course, assoon as the discharge current through the primary winding 14 has ceasedto flow and as soon as the capacitor 51 has become discharged, thejunction point between the resistors 29 and 50 is again at the groundpotential and therefore the transistor 52 now remains conductive but dueto the open condition of the switch 18 as described above. The closingof the breaker switch at this time, with the junction point between theresistors 29 and 50 at the ground potential, would cause the transistor52 to become nonconductive to thereby again turn the switchingtransistor 15 on and cause a current to flow through the primary winding14 to reestablish a field thereabout. By selecting the value of thecapacitor 51 and the resistors 29, 50 and 57, the time constant of thesecond circuit may be selected so that the momentary closing of thebreaker switch 18 can be compensated for within a range of time afterinitial opening.

The blocking diode 49 is provided to prevent a rapid discharge of thecapacitor 51 by a closing of the breaker switch 18. Thus, whenever thecapacitor 51 has a voltage thereacross the breaker switch 18 closes, theblocking diode 49 automatically becomes nonconductive and the rapiddischarge of the capacitor is thereby prevented.

In connection with the embodiments 1-3 above, the second circuit hasbeen connected to the primary winding 14, the latter providing theenergy which has been stored during the closed condition of the breakerswitch 18 to prevent the closing of-the switching transistor duringmomentary closing of the breaker switch after a normal opening thereof.In the two embodiments that follow, a separate energy storing element isutilized for the purpose of storing energy when the breaker switch 18is-closed during the normally closed interval and this stored energy isutilized for the purposes described above. Referring first to FIG. 4,the control circuit of the first circuit here consists of a resistor 26which is connected between the positive supply lead 23 and the breakerswitch 18. The tap point between the resistor 26 and the switch 18 isconnected to the control electrode 24 through two resistors 57 and 60which are connected in series with one another. The driving circuit ofthe first circuit comprises a npn transistor 52 whose base 56 comprisesthe control electrode 24. The emitter 53 of the transistor 52 isconnected to the negative supply lead 21 while its collector 55 isconnected to the positive supply lead 23 through a collector-resistor54. A second driving transistor 63 has its base 62 connected to thecollector 55 of the transistor 52 through a limiting resistor 62. Theemitter 64 of the transistor 63 is connected to thenegative supply lead21 while the collector 65 thereof is connected to the positive supplylead 23 through a set of series connected resistors 66 and 67 forming atap point 70. Here, the switching transistor 68 has a base 69 connectedto the tap point 70 of the voltage divider while its emitter-collectorpath 71-72 is respectively connected between the positive supply lead 23and the primary winding 14. The second circuit in this embodimentcomprises a diode 59 connected in parallel with the resistor 60 in adirection to conduct current from the resistor 26 towards the resistor57. Also, the second circuit consists of a storage capacitor 58 which isconnected between the cathode of the diode 59 and the negative supplylead 21. As illustrated in FIG. 4, the

transistors 52 and 63 are selected to be of the npn type while theswitching transistor 68 is selected to be of the p YP- The operation ofthe embodiment shown in FIG. 4 will now be described. During normalinitial closing of the breaker switch 18, the tap point between theresistor 26 and the breaker switch 18 is placed at ground potential sothat the control electrode 24 is not sufficiently positive to cause thetransistor 52 to become conductive. With the transistor 52non-conductive, the collector 55 thereof is sufficiently positive inrelation to the emitter 64 of the transistor 63, that the lattertransistor becomes conductive and a current flows from the positivesupply lead 23 through the resistors 66 and 67 through thecollector-emitter path 65-64 towards the negative supply lead 21. Thecurrent flowing through this voltage divider develops a voltage at thetap point 70 which is sufficiently negative in relation to the emitter71 of the transistor 68 so that the latter transistor becomes conductiveand current flows through the emitter-collector path 71-72 into theprimary winding 14 where energy is stored as described above.

When the breaker switch 18 initially opens during its open interval, thejunction point between the resistor 26 and breaker switch 18 becomeshighly positive so that the diode 59 becomes conductive in a forwarddirection and a current flows therethrough to both provide a basecurrent in the base 56 as well as to provide a charging current tocharge the capacitor 58. Thus, when the breaker switch opens, thetransistor 52 becomes conductive and its collector 55 drops sharply inthe negative direction to a point where it is no longer sufficientlypositive in relation to the emitter 64 of the transistor 63, to maintainthe conductive state of the latter. With the transistor 63 turned off,the current originally flowing through the resistors 66 and 67 ceasesand the voltage at the tap point 70 rises sharply towards the voltage ofthe positive supply lead 23. The rise in voltage at the tap point 70 nolonger places the base 69 at a voltage sufficiently negative withrespect to the emitter 71 of the transistor 68 to maintain the latter ina conductive state and the transistor becomes non-conductive. Inaccordance with the operation described above, such an abrupt change incurrent in the primary winding 14 causes a very high induced voltage inthe secondary winding 12 to thereby produce a spark across the sparkplug13. As long as the breaker switch 18 remains open, current continues toflow from the positive supply lead 23, the resistor 26, the diode 59into the storage capacitor 58 to charge the same. The current flowingthrough the diode 59 also produces the base current for the transistor52 as described above. Should the breaker switch 18 now momentarilyclose after initial opening, the anode of the diode 59 is placed at theground potential while its cathode is at the potential developed acrossthe capacitor 58. Therefore, the diode 59 becomes non-conductive.However, the capacitor 58 has sufficient charge stored thereon so thatit may continue to supply a base current through the resistor 57 to thetransistor 52 to maintain the same in a conductive state in spite of amomentary closing of the switch 18. The time during which the transistor52 can be so maintained conductive when the switch 18 is closed isdetermined by the time constant of the capacitor 58 and the resistors 57and Y60. It will be noted that the operation of the embodiments in FIG.4 is somewhat different than that discussedpreviously in relation tothe. embodiments of FIGS. l,-3. Thus, in the earlier embodiments, theenergy stored for purposes of cornpensating for momentary closings ofthe breaker switch 18 was the same energy stored during a normal closingof the switch 18. In the embodiment of FIG. 4, however, the energystored for this purpose is not stored during the normal closing of thebreaker switch 18 but is rather stored during the short initial openinginterval of the breaker switch 18 prior to theundesired momentaryclosing thereof.

In the circuits of FIG. 4, the discharge resistor 60 is so chosen thatthe storage capacitor 58 after the closing of the breaker switch 18discharges the latter in a relatively short period of time during thenormal closing interval of the switch. However, the discharge current ismade small enough so that the capacitor 60 does not fully dischargeduring the anticipated time intervals during which the breaker switch 18is contemplated to momentarily close after a normal opening of theswitch. In this manner. the storage capacitor 58 acts as a source ofvoltage during the critical time intervals when the breaker switch 18may close to maintain the control electrode 24 potential the same as itwould be were the breaker switch 18 to remain continuously open. Thediode 59 is selected to conduct current in the direction described aboveto thereby permit a quick charging of the storage capacitor 58 whilepreventing an equally rapid discharging thereof when the switch I8closes.

The ignition system illustratd in FIG. differs from the previousembodiments in that the driving circuit has been totally eliminated fromthe first circuit. Here the control circuit of the first circuit,similarly to that in FIG. 2, consists of a pair of resistors 26 and 27connected in series with each other to form a voltage divider betweenthe positive supply lead 23 and the breaker switch 18. A diode 48 isconnected between the resistors 26 and 27, the resistor 26 and the anodeof the diode 48 forming a tap point which is. connected to the controlelectrode 24. A storage meanssimilar to that in FIG. 4 is utilized hereand this consists of the storage capacitor 58. The second circuit inthis embodiment is similar to that described in connection with FIG. 2except that the second circuit is not dependent here upon energy storagefrom the primary winding 14 but rather from the energy stored inthe'capacitor 58. Thus, the second circuit here comprises a transistor39 whose emitter is connected to the positive supply lead 23 and itscollector is connected to the cathode of the diode 48. The base 42 ofthe transistor 39 is connected to the collector 46 of the transistor 44.The transistor 39 is a pnp transistor While the transistor 44 is an npntransistor. The emitter 45 of the transistor 44 is connected to thenegative supply lead 21 while its base 47 is connected to the storagecapacitor 58 through a limiting resistor 73. As in FIG. 4, the storagecapacitor 58 is connected to a source of current by means of a diode 59and a parallel connected resistor 60. In this case, the diode 59 andresistor 60 are connected between the storage capacitor 58 and thecathode of the diode 48.

the transistor 44 is substantially at the same potential as its emitterso that the transistor 44 is in a non-. conductive state. This, as willbe described, also causes the transistor 39 to, the non-conductive. Withthe breaker switch 18 closed, the series connected resistors 26 and 27as well as the diode 48 areplacedacross the positive and negative supplyleads 23 and 21 respectively so that a current flows from the former tothe latter. In this state, the diode 48 is conductive and a voltage isdeveloped across-the resistor 26 which is sufiiciently high to apply tothe control electrode 24 or the base 69 a sufficiently high negativevoltage in relation to that appearing at the emitter 71 of the switchingtransistor 68 so that the latter becomes conductive and a collectorcurrent flows through the collector 72 into the primary winding I4.Energy is stored in the primary winding 14 during the normally closedinterval of the breaker switch 18.

When the breaker switch opens, assuming that. the second circuit werenot provided, the current flow in the resistor 26 is interrupted so thatthe control electrode 24 attains the positive potential present as thepositive supply lead to thereby equalize the voltages at the emitter 7land the base 69 whereby the switching transistor 68 is madenon-conductive. Therewith, the current flow in the primary winding I4 isinterrupted and a high voltage is induced in the secondary winding 12 tothereby generate a spark across the spark gap 13.

Were a second circuit not be provided, a momentary closing of thebreaker switch 18 after initial opening would produce a closing of theemitter-collector path 71472. This would result in the disadvantagesdiscussed above. However, with the second circuit provided as shown, theopening of the breaker switch 18 raises the potential of the anode ofthe diode 59 sufficiently to make the same conductive and a currentflows through the positive supply lead 23, through the resistor 26,diode 48, the diode 59 to the storage capacitor 58. The current flowingthrough the diode 59 charges the capacitor 58 as well as provides a basecurrent which flows through the resistor 73 into the base 47 to therebyturn the transistor 44 on or to make the emitter-collector path 45-46conductive. Since the transistor 39 is of the pnp type and thetransistor 44 is of the npn type, current flow in the collector 46 formsa base current in the base 42 which is effective to make the transistor39 similarly conductive. When the emittercollector path 40-41 of thetransistor 39 becomes conductive, it presents a virtual short circuitbetween the positive supply lead 23 and the anode of the diode 59 tothereby place the latter at such a high positive potential that amomentary closing of the breaker switch 18 does not bring the cathode ofthe diode 48 to a sufficiently negative voltage to turn the latter diodeon. As long as the diode 48 remains in its non-conductive state, nocurrent can flow through the resistor 26 and the transistor 68 remainsnon-conductive. As in the embodiment shown in FIG. 4, the time duringwhich momentary closings of the breaker switch 18 can be masked is afunction of the time constant of the capacitor 58 as well as theresistors 60 and 27. Now, when the breaker switch 18 momentarily closesafter initial opening, the anode of the diode 59 is placed at a morenegative potential than its cathode so that it becomes non-conductive.However, the charge on the capacitor 58 is still sufficiently positiveto continually supply a base current to the base 47 of the transistor44. As long as this occurs, the transistor 39 remains conductive and theswitching transistor 68 is prevented from turning on. Ultimately, whenthe breaker switch 18 opens again, the capacitor 58 discharges throughthe resistors 27 and 60. When this occurs, the base 47 is substantiallyat the same potential as the emitter 45 so that the transistor 44becomes non-conductive and thereby the transistor 39 similarly becomesnon-conductive. Under these conditions, the cathode of the diode 48drops towards the negative potential and becomes conductive whereby thecontrol electrode 24 becomes more negative in respect to the emitter 71and the switching transistor 68 can once again conduct.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconrol circuit differing from the types described above.

While the invention has been illustrated and described as embodied inignition systems for internal combustion engines, it is not intended tobe limited to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

I. In an ignition system for an internal combustion engine of the typeincluding an ignition transformer comprised of a primary winding and asecondary winding and spark producing means connected across saidsecondary winding. in combination therewith, a rotary element driven byand rotating in synchronism with the engine; an ignition breaker switchcoupled to said rotary element and arranged to be open during first timeintervals corresponding to first predetermined ranges of angularpositions of said rotary element and to be closed during second timeintervals alternating with said first time intervals and correspondingto second predetermined ranges of angular positions of said rotaryelement; switching means connected in the current path of said primarywinding and operative when open for preventing flow of current throughsaid primary winding through such current path and operative when closedfor permitting flow of current through said primary winding through suchcurrent path; first circuit means connected between said ignitionbreaker switch and said switching means and normally operative forcausing said switching means to open when said breaker switch opens andfor causing said switching means to close when said breaker switchcloses; and second circuit means connected to said first circuit meansand operative if due to faulty operation said breaker switch brieflycloses during one of said first time intervals for maintaining saidswitching means open despite such brief closing of said breaker switch.

2. A combination as defined in claim 1, wherein said first circuit meanscomprises driving means connected to said switching means and having acontrol electrode; and signal control means connected to said breakerswitch and to said control electrode for generating signals during saidfirst and second intervals in response to opening andclosing of saidbreaker switch at said control electrode which causes said driving meansto correspondingly open andclose said switching means.

3. A combination as defined in claim 2, wherein said second circuitmeans is connected to said control electrode and is arranged to maintainsaid driving means in a condition wherein the latter prevents saidswitching means from closing during at least portions of said firstintervals.

4. A combination as defined in claim 3, wherein said first circuit meansfurther comprises first and second leads each connectable to arespective pole of a source of electrical energy, connected primarywinding and switching means being connected in series between said firstand second leads, said ignition breaker switch having two terminals oneof which is connected to one of said leads and the other terminal ofwhich is connected to said control electrode.

5. A combination as defined in claim 4, wherein said one of said leadsto which said one terminal is connected constitutes said second lead,and wherein said first circuit means further comprises first resistancemeans connected between said first lead and said other terminal of saidignition breaker switch.

6. A combination as defined in claim 5, wherein said first circuit meansfurther comprises second resistance means connected between said firstresistance means and said other terminal of said ignition breakerswitch, said first and second resistance means forming a tap pointconnected to said control electrode.

7. A combination as defined in claim 5, wherein said series connectedprimary winding and switching means form a tap point, said tap pointbeing connected to said other terminal of said ignition breaker switch.

8. A combination as defined in claim 7, further comprising capacitormeans connected between said tap point and one of said first and secondleads.

9. A combination as defined in claim 8, wherein said capacitor means isconnected between said tap point and said second lead.

10. A combination as defined in claim 4, wherein said first circuitmeans comprises capacitor means for storing electrical energy when saidignition breaker switch is open during said first intervals, saidcapacitor means being arranged to discharge said electrical energyduring said at least portions of said first intervals to thereby apply amaintaining signal to said control electrode for maintaining saidswitching means open during said portions of said first intervals.

11. A combination as defined in claim 4, wherein said second circuitmeans includes a discharge conductor lead connecting the tap pointbetween said series connected primary winding and switching means withsaid control electrode.

12. A combination as defined in claim 11, wherein said second circuitmeans further comprisesa resistance connected between said dischargeconductor lead and said control electrode.

13. A combination as defined in claim 12, wherein said second. circuitmeans further comprises a voltage reference means connected in serieswith said resistance and said discharge conductor lead.

14. A combination as defined in claim 13, wherein said voltage referencemeans comprises a Z'ener diode.

15. A combination as defined in claim 12, wherein said second circuitmeans further comprises diode means connected in series with saidresistance and said discharge conductor lead.

l6. Acombination as defined in claim 11, wherein said one leadconstitutes said second lead, and wherein said first circuit meanscomprises first resistance means connected between said first lead andsaid other terminal of said ignition breaker switch, and said dischargeconductor lead being connected to said other terminal.

17. A combination as defined in claim 6, said second circuit meansfurther comprises a switch connected between said first lead and saidtap point, said switch being actuable during said portions of said firstintervals to maintain said switching means open irrespective of closingof said ignition breaker switch during said portions.

18. A combination as defined in claim 17, wherein said switch comprisesa switching transistor having its emitter-collector path connectedbetween said first lead and said tap point, and having its base actuatedduring said portions of said first intervals to close said path tothereby'm-aintain said switching means open during said intervalportions.

19. A combination as defined in claim 6, further comprising diode meansconnected between said first and second resistance means arranged toconduct current from the former to the latter.

20. A combination as defined in claim 18, wherein said second circuitmeans further comprises a control transistor having itsemitter-collector path connected between the base of said switchingtransistor and said second lead. and having a base actuable during saidportions of said first intervals, to thereby close said switchingtransistor emitter-collector path.

21. A combination as defined in claim 20, wherein said second circuitmeans includes a discharge conductor lead connecting the tap pointbetween said series connected primary winding and switching means withsaid control electrode, said discharge conductor being connected to thebase of said control transistor.

22. A combination as defined in claim 5, further comprising diode meansconnected'between said other terminal of said ignition breaker means andthe junction of said primary winding and said switching means.

23. A combination as defined in claim 22, wherein said diode meanscomprises a diode arranged to conduct current which flows from saidfirst lead through said first resistance means duringsaidportions ofsaid intervals, said diode also being connected to said'controlelectrode.- I

24. A combination as defined in claim 23, wherein said second circuitmeans further comprises first and second resistors connected in serieswith oneanother, said series connected resistors being connected inparallel to said switching means.

25. A combination as defined-in claim 24, wherein said first and secondresistors forma tap point, said second circuit means further comprisingcapacitor means connected between said tap'point-and'said second lead,said tap point also being connected between said diode and said controlelectrode. 7 a

26. A combinationas defined in claim '5,'wherein'said second circuitmeans further comprises diode means connected between said otherterminaland said control electrode; and capacitor means connectedbetween said control electrode and saidsecond lead.

27. A combination as defined'in claim 26, wherein said diode meanscomprises a diode ari'ang ed to'conduct current in a direction from said*firstresistance meanstowards said control electrode. i

28. A combination as defined in claim 26, further including resistormeans connected in parallel with said diode means. i

29. A combination'as defined in claim 26, further including secondresistance means connectedbetween said other terminal and said diodemeans.- a

30. A combination as defined in claim 26, wherein said second circuitmeans further includes a transistor having its base connected tosaid'diode'means andits emitter-collector path-connected between saidsecond lead and said control electrode.

31. A combination as'defined in claim 30,-further comprising aresistance connected between said diode means and the base of'saidtransiston 32. A combination as defined in claim 4, wherein said drivingmeans comprises a transistor having its'emittercollectorpath'connectedbetweensaid'first and second leads, and having its baseconnected to said control electrode, said transistor being connected tosaid switching means for controlling the'ope'n and closed states of thelatter. i 3

33. A combination as defined in claim 4, wherein said switching meanscomprises a transistor having its emitter-collector path connected inseries with said primary winding andhaving its base directly connectedto said control electrode. Y 1

34. A combination as defined in claim 4,wher'ein said driving meanscomprises a transistor'having it's emittercollector path-connectedbetween said first and second leads; said signal control meanscomprising first and second resistance means connected in series witheach other and with said breaker switch between said first and secondleads to form a tap, said tap being connected to the base of saidtransistor, said transistor being connected to said switching means forcontrolling the open and closed states of the latter.

35. A combination as defined in claim 34, further comprising diode meansconnected between said first and second resistance means, the base ofsaid transistor being connected to a tap point formed by said diodemeans and one of said resistance means.

36. A combination as defined in claim 35, wherein said first resistancemeans is connected to said first lead, said second resistance isconnected to said second lead, and the base of said transistor isconnected to a tap point formed by saidfirst resistance means and saiddiode means.

37. A combination as defined in claim 4, wherein said driving meanscomprises a transistor having its emittercollector path connectedbetween said first and second leads; said signal control meanscomprising first resistance means connected in series to said breakerswitch to form a tap, the latter series combination being connectedbetweensaid first and second leads, the base of said transistor beingconnected to said tap.

38. A combination as defined in claim 37, further comprising diode meansconnected between the said base and said tap.

39. A combination as defined in claim 38, wherein said diode meanscomprise a diode arranged to conduct current from said tap to said base.

40. A combination as defined in claim 38, further comprising resistancemeans connected between said diode means and said base.

41. In an ignition system for an internal combustion engine of the typeincluding an ignition transformer comprised of a primary winding and asecondary winding and spark producing means connected across saidsecondary winding, in combination therewith, a rotary element driven byand rotating in synchronism with the engine; an ignition breaker switchcoupled to said rotary element and arranged to be open during first timeintervals corresponding to first predetermined ranges of angularpositions of said rotary element and to be closed during second timeintervals alternating with said first time intervals and correspondingto second predetermined ranges of angular positions of said rotaryelement; switching means connected in the current path of said primarywinding and operative when open for preventing flow of current throughsaid primary winding through such current path and operative when closedfor permitting flow of current through said primary winding through suchcurrent path; first circuit means connected between said ignitionbreaker switch and said switching means and normally operative forcausing said switching means to open when said breaker switch opens forcausing said switching means to close when said breaker switch closes,and wherein said primary winding constitutes an energy storing elementwhich stores energy during said second intervals; and second circuitmeans operative for utilizing at least part of the energy stored in saidprimary winding for maintaining said switching means open during briefclosing of said breaker switch in the event that due to faulty operationsaid breaker switch briefly closes during one of said first timeintervals, and wherein said switching means includes an electronicswitch element having a current path connected in said current path ofsaid primary winding and having a control electrode connected to andcontrolled by said first circuit means. =l

1. In an ignition system for an internal combustion engine of the typeincluding an ignition transformer comprised of a primary winding and asecondary winding and spark producing means connected across saidsecondary winding, in combination therewith, a rotary element driven byand rotating in synchronism with the engine; an ignition breaker switchcoupled to said rotary element and arranged to be open during first timeintervals corresponding to first predetermined ranges of angularpositions of said rotary element and to be closed during second timeintervals alternating with said first time intervals and correspondingto second predetermined ranges of angular positions of said rotaryelement; switching means connected in the current path of said primarywinding and operative when open for preventing flow of current throughsaid primary winding through such current path and operative when closedfor permitting flow of current through said primary windiNg through suchcurrent path; first circuit means connected between said ignitionbreaker switch and said switching means and normally operative forcausing said switching means to open when said breaker switch opens andfor causing said switching means to close when said breaker switchcloses; and second circuit means connected to said first circuit meansand operative if due to faulty operation said breaker switch brieflycloses during one of said first time intervals for maintaining saidswitching means open despite such brief closing of said breaker switch.2. A combination as defined in claim 1, wherein said first circuit meanscomprises driving means connected to said switching means and having acontrol electrode; and signal control means connected to said breakerswitch and to said control electrode for generating signals during saidfirst and second intervals in response to opening and closing of saidbreaker switch at said control electrode which causes said driving meansto correspondingly open and close said switching means.
 3. A combinationas defined in claim 2, wherein said second circuit means is connected tosaid control electrode and is arranged to maintain said driving means ina condition wherein the latter prevents said switching means fromclosing during at least portions of said first intervals.
 4. Acombination as defined in claim 3, wherein said first circuit meansfurther comprises first and second leads each connectable to arespective pole of a source of electrical energy, connected primarywinding and switching means being connected in series between said firstand second leads, said ignition breaker switch having two terminals oneof which is connected to one of said leads and the other terminal ofwhich is connected to said control electrode.
 5. A combination asdefined in claim 4, wherein said one of said leads to which said oneterminal is connected constitutes said second lead, and wherein saidfirst circuit means further comprises first resistance means connectedbetween said first lead and said other terminal of said ignition breakerswitch.
 6. A combination as defined in claim 5, wherein said firstcircuit means further comprises second resistance means connectedbetween said first resistance means and said other terminal of saidignition breaker switch, said first and second resistance means forminga tap point connected to said control electrode.
 7. A combination asdefined in claim 5, wherein said series connected primary winding andswitching means form a tap point, said tap point being connected to saidother terminal of said ignition breaker switch.
 8. A combination asdefined in claim 7, further comprising capacitor means connected betweensaid tap point and one of said first and second leads.
 9. A combinationas defined in claim 8, wherein said capacitor means is connected betweensaid tap point and said second lead.
 10. A combination as defined inclaim 4, wherein said first circuit means comprises capacitor means forstoring electrical energy when said ignition breaker switch is openduring said first intervals, said capacitor means being arranged todischarge said electrical energy during said at least portions of saidfirst intervals to thereby apply a maintaining signal to said controlelectrode for maintaining said switching means open during said portionsof said first intervals.
 11. A combination as defined in claim 4,wherein said second circuit means includes a discharge conductor leadconnecting the tap point between said series connected primary windingand switching means with said control electrode.
 12. A combination asdefined in claim 11, wherein said second circuit means further comprisesa resistance connected between said discharge conductor lead and saidcontrol electrode.
 13. A combination as defined in claim 12, whereinsaid second circuit means further comprises a voltage reference meansconnected in series with said resistance and said dischargE conductorlead.
 14. A combination as defined in claim 13, wherein said voltagereference means comprises a Zener diode.
 15. A combination as defined inclaim 12, wherein said second circuit means further comprises diodemeans connected in series with said resistance and said dischargeconductor lead.
 16. A combination as defined in claim 11, wherein saidone lead constitutes said second lead, and wherein said first circuitmeans comprises first resistance means connected between said first leadand said other terminal of said ignition breaker switch, and saiddischarge conductor lead being connected to said other terminal.
 17. Acombination as defined in claim 6, said second circuit means furthercomprises a switch connected between said first lead and said tap point,said switch being actuable during said portions of said first intervalsto maintain said switching means open irrespective of closing of saidignition breaker switch during said portions.
 18. A combination asdefined in claim 17, wherein said switch comprises a switchingtransistor having its emitter-collector path connected between saidfirst lead and said tap point, and having its base actuated during saidportions of said first intervals to close said path to thereby maintainsaid switching means open during said interval portions.
 19. Acombination as defined in claim 6, further comprising diode meansconnected between said first and second resistance means arranged toconduct current from the former to the latter.
 20. A combination asdefined in claim 18, wherein said second circuit means further comprisesa control transistor having its emitter-collector path connected betweenthe base of said switching transistor and said second lead, and having abase actuable during said portions of said first intervals, to therebyclose said switching transistor emitter-collector path.
 21. Acombination as defined in claim 20, wherein said second circuit meansincludes a discharge conductor lead connecting the tap point betweensaid series connected primary winding and switching means with saidcontrol electrode, said discharge conductor being connected to the baseof said control transistor.
 22. A combination as defined in claim 5,further comprising diode means connected between said other terminal ofsaid ignition breaker means and the junction of said primary winding andsaid switching means.
 23. A combination as defined in claim 22, whereinsaid diode means comprises a diode arranged to conduct current whichflows from said first lead through said first resistance means duringsaid portions of said intervals, said diode also being connected to saidcontrol electrode.
 24. A combination as defined in claim 23, whereinsaid second circuit means further comprises first and second resistorsconnected in series with one another, said series connected resistorsbeing connected in parallel to said switching means.
 25. A combinationas defined in claim 24, wherein said first and second resistors form atap point, said second circuit means further comprising capacitor meansconnected between said tap point and said second lead, said tap pointalso being connected between said diode and said control electrode. 26.A combination as defined in claim 5, wherein said second circuit meansfurther comprises diode means connected between said other terminal andsaid control electrode; and capacitor means connected between saidcontrol electrode and said second lead.
 27. A combination as defined inclaim 26, wherein said diode means comprises a diode arranged to conductcurrent in a direction from said first resistance means towards saidcontrol electrode.
 28. A combination as defined in claim 26, furtherincluding resistor means connected in parallel with said diode means.29. A combination as defined in claim 26, further including secondresistance means connected between said other terminal and said diodemeans.
 30. A combination as definEd in claim 26, wherein said secondcircuit means further includes a transistor having its base connected tosaid diode means and its emitter-collector path connected between saidsecond lead and said control electrode.
 31. A combination as defined inclaim 30, further comprising a resistance connected between said diodemeans and the base of said transistor.
 32. A combination as defined inclaim 4, wherein said driving means comprises a transistor having itsemitter-collector path connected between said first and second leads,and having its base connected to said control electrode, said transistorbeing connected to said switching means for controlling the open andclosed states of the latter.
 33. A combination as defined in claim 4,wherein said switching means comprises a transistor having itsemitter-collector path connected in series with said primary winding andhaving its base directly connected to said control electrode.
 34. Acombination as defined in claim 4, wherein said driving means comprisesa transistor having its emitter-collector path connected between saidfirst and second leads; said signal control means comprising first andsecond resistance means connected in series with each other and withsaid breaker switch between said first and second leads to form a tap,said tap being connected to the base of said transistor, said transistorbeing connected to said switching means for controlling the open andclosed states of the latter.
 35. A combination as defined in claim 34,further comprising diode means connected between said first and secondresistance means, the base of said transistor being connected to a tappoint formed by said diode means and one of said resistance means.
 36. Acombination as defined in claim 35, wherein said first resistance meansis connected to said first lead, said second resistance is connected tosaid second lead, and the base of said transistor is connected to a tappoint formed by said first resistance means and said diode means.
 37. Acombination as defined in claim 4, wherein said driving means comprisesa transistor having its emitter-collector path connected between saidfirst and second leads; said signal control means comprising firstresistance means connected in series to said breaker switch to form atap, the latter series combination being connected between said firstand second leads, the base of said transistor being connected to saidtap.
 38. A combination as defined in claim 37, further comprising diodemeans connected between the said base and said tap.
 39. A combination asdefined in claim 38, wherein said diode means comprise a diode arrangedto conduct current from said tap to said base.
 40. A combination asdefined in claim 38, further comprising resistance means connectedbetween said diode means and said base.
 41. In an ignition system for aninternal combustion engine of the type including an ignition transformercomprised of a primary winding and a secondary winding and sparkproducing means connected across said secondary winding, in combinationtherewith, a rotary element driven by and rotating in synchronism withthe engine; an ignition breaker switch coupled to said rotary elementand arranged to be open during first time intervals corresponding tofirst predetermined ranges of angular positions of said rotary elementand to be closed during second time intervals alternating with saidfirst time intervals and corresponding to second predetermined ranges ofangular positions of said rotary element; switching means connected inthe current path of said primary winding and operative when open forpreventing flow of current through said primary winding through suchcurrent path and operative when closed for permitting flow of currentthrough said primary winding through such current path; first circuitmeans connected between said ignition breaker switch and said switchingmeans and normally operative for causing said switching means to openwhen said breakeR switch opens for causing said switching means to closewhen said breaker switch closes, and wherein said primary windingconstitutes an energy storing element which stores energy during saidsecond intervals; and second circuit means operative for utilizing atleast part of the energy stored in said primary winding for maintainingsaid switching means open during brief closing of said breaker switch inthe event that due to faulty operation said breaker switch brieflycloses during one of said first time intervals, and wherein saidswitching means includes an electronic switch element having a currentpath connected in said current path of said primary winding and having acontrol electrode connected to and controlled by said first circuitmeans.